Fluidic fuel system

ABSTRACT

Fluidic amplifiers responsive to vacuum air signals developed in an engine intake manifold to control fuel delivery to the engine. Fluidic elements are immersed in a fuel containing reservoir with air vacuum control signals applied at a downstream location through an output leg of the fluidic elements and an atmospheric air bleed is provided in the output leg in a horizontal plane above the fluidic elements and reservoir.

O United States Patent 151 3,675,906

Baldwin et al. 51 July 11, 1972 s41 FLUIDIC FUEL SYSTEM 3,388,898 6/1968 Wyczalek 261/D1G. 69 3,477,699 11/1969 Drayer.... ..261/DlG, 69 [721 Invent r s"; m 3,539,157 11/1970 Fort ..261/D1G. 69 3,544,082 12/1970 Fort ..261/D1G. 69 [73] Assignee: The Bendix Corporation 3,556,488 1/1971 Arikawa et a] ..261/36 A [22] Fl d Se t 25 1970 3,574,346 4/1971 Sulich ..261/36 A 1 e p [211 App] 75,634 Primary Examiner-Tim R. Miles AttorneyWi1liam S. Thompson and Plante, l-lartz, Smith and Thompson [52] U.S. Cl. ..26l/23 A, 261/36 A, 261/69 R,

261/72, 261/121 A, 261/D1G. 69, 137/815, [57] ABSTRACT 123/D1G. 10 [51] Int. Cl ..F02m 69/04 ampllfiers responswe to vacuum s'gnals developed 58] Field of Search 26 HDIG 69 72 36 A 69 R in an engine intake manifold to control fuel delivery to the en- /23 l i gine. Fluidic elements are immersed in a fuel containing reservoir with air vacuum control signals applied at a downstream location through an output leg of the fluidic elements and an [56] References cued atmospheric air bleed is provided in the output leg in a UNITED STATES PATENTS horizontal plane above the fluidic elements and reservoir.

3,288,445 11/1966 Mennesson ..261/36 A 10 Claims, 1 Drawing Figure v74 la '12 48 so U1 6 -75 (I 2 as 24 a2 4 j-1 6o 66 as] 113 1m k 56 e4 1 6a 42 T -gz Q4 32 52 30 a as 62 94 214m, 1 2 1 J PKTE'N'TEDJIJL 1 1 I972 3.675 906 WALTON B. BALDWIN DONALD A. BURGER INVENTORY FLUIDIC FUEL SYSTEM BACKGROUND OF INVENTION The broad idea of utilizing fluidic elements to perform the fuel controlling function for an internal combustion engine is known, particularly in the patent and technical literature. Concepts have been proposed and demonstrated, but so far none have obtained commercial acceptance. One known approach utilizes pressurized liquid fuel at the main power jet of a fluidic element and various pneumatic subatmospheric air signals derived from the intake air manifold or carburetor body at the control jets. This permits the use of traditional Venturi and manifold vacuum signals which have established their validity through decades of use in the carburetor field. In this case, however, the fluidic element or elements require the capability of handling two different fluids, liquid fuel on the one hand and an air vacuum on the other, which exposes the problem of one fluid becoming entrained in the other and upsetting the metering balance. This problem was recognized in copending commonly assigned U.S. Pat. application Ser. No. 754,505 filed Aug. 21, 1968 in the name of Janusz S. Sulich, now U.S. Pat. No. 3,574,346, and entitled Fuel System where the use of air to liquid transducers was proposed so that the pneumatic signals could be converted to liquid signals and the fluidic elements could operate as liquid on liquid rather than air on liquid devices. While that solution is functionally adequate, providing a transducer at each air to liquid interface point imposes considerable complexity and cost and is antagonistic to the promise that fluidic elements may lead to a low cost carburetion scheme.

SUMMARY OF INVENTION It is an object of this invention to provide a fuel system for an internal combustion engine which utilizes fluidic elements and reacts to subatmospheric air pressure signals to deflect a liquid fuel jet, but which avoids fuel/air entrainment problems without the need of special air/fuel signal transducers.

This objective is achieved essentially by isolating the fluidic element so that all fluid inputs are liquid fuel and the fluidic element or elements are essentially single fluid elements. The subatmospheric pressure signals are then applied through an output delivery passage leading from the fluidic element and downstream from the fluidic element. The output delivery passage has a portion which is at an elevation higher than the fluidic elements which is vented to the atmosphere through a known bleed restriction. Under this arrangement the air fluid signal is felt only downstream of the fluidic elements and, as will become apparent from the detailed description, avoids uncontrolled air entrainment problems.

BRIEF DESCRIPTION OF DRAWING The single FIGURE is a schematic drawing of a two-barrel carburetor having a fluidic element metering section arranged in accordance with the teachings of this invention.

DETAILED DESCRIPTION Referring to the drawing, there is shown a schematic representation of a two-barrel carburetor and fluidic fuel metering device. The two carburetor barrels or air intake passages and 12, for functional convenience of illustration, are spaced apart. Each intake passage has an air receiving opening 14, 16; an eccentrically mounted plate type choke valve segment 18, a main Venturi section 22, 24; a control throttle plate valve segment 26, 28; and a discharge air opening 30, 32 which is adapted to be connected to an engine manifold. In the non-schematicized form of the two-barrel carburetor, openings 14 and 16 receive air from a common source or opening, usually from an air filter, and discharge openings deliver a fuel/air charge to a common manifold. Also, choke valve segments 18 and 20 and throttle valve segments 26 and 28 are mounted on common choke and throttle valve shafts, thus each comprising sub-elements of the total valve structure.

The fuel detennining and control apparatus consists of air sensing and fuel delivery ports located in each carburetor barrel or intake passage and a fluidic fuel metering section generally designated by the numeral 34. In the preferred arrangement, air sensing and fuel delivery ports are arranged to provide separate main fuel and idle fuel delivery points similar to current carburetor practice. Referring to intake passage 10, a main metering section consists of fuel delivery tube 36 having an opening disposed in the center of a low pressure region in small Venturi 38. An idle fuel delivery jet 40 is located downstream of throttle plate 26 where it is exposed to vacuum present in the engine manifold. Adjustable restriction 42 is provided in the idle jet circuit to provide an idle fuel adjustment device. Passage 44 interconnects the main and idle fuel delivery jets and also is connected with an air bleed 46 which is located intermediate the main and idle fuel locations and assists in the transition from one to the other. A similar main fuel delivery tube 48, small Venturi 50, idle jet 52 are present in the second carburetor barrel 12.

The fuel metering section 34 consists of a fuel reservoir 54 containing fuel to a controlled level indicated by dashed line A which may be similar to standard carburetor float level controlled fuel reservoirs or a weir controlled reservoir system as taught in commonly assigned copending U.S. Pat. application Ser. No. 841,840 entitled Fluidic Control System with Back Pressure Control filed in the name of Donald F. Morgan.

A pair of beam deflection proportional fluidic elements 56 and 58 are contained in reservoir 54 below the fuel level A whereby they are immersed in the fuel. Referring particularly to fluidic element 56, it consists of a main fluid jet 60 which receives pressurized fuel from manifold point 62 which is adapted to be connected to a liquid fuel pressurizing pump, not shown. Some pressurized fuel is also bled through passage 64 to the obliquely aligned jet 66 to provide a slight bias to the left of the main stream issuing from jet 60. Other biasing means are known and may be employed, such as non-symmetrical location of the fluidic divider, main jet or the like. Downstream of main jet 60 the two receiver passages 68 and 70 are located. Passage 68 terminates (is open) within reservoir 54 at a point below fuel level A. Receiver passage 70 is connected to a first branch 72 of a fuel output passage. Output passage 72 connects to passage 74 which projects vertically upward and extends to a point above the fuel level A where it is open to the atmosphere through a sized restriction 76. Passage 72 is also connected to metered fuel passage 78 which in turn is connected to the previously described passage 44 of the carburetor main and idle fuel system. Receiver passage 70, at its junction with output passage 72, is further connected to control jet 73 through passage for purposes that will be later described.

Fluidic element 58 provides the same function and is similarly arranged as element 56 to provide a metered fuel supply to the second carburetor barrel 12. For a single barrel carburetor this element may be eliminated. Since element 58 performs the same as element 56 it is not separately described. It is noted that elements 56 and 58 may be cross coupled as by passage connection 80 at their output passages to effect a balance in the various parallel fuel conditioning barrels.

As will later be discussed in more detail, fluidic element 56 will provide a rate of fuel delivery proportional to the mass air flow to the carburetor barrel 14 establishing the basic idle and main fuel supply. As is known in the carburetor art, secondary fuel enrichment devices are required to meet high power conditions. In the present invention a fuel augmenting device is added to the system by utilizing fluidic devices and the entrainment problem controlled by immersing such devices in the reservoir 54. A power enrichment fuel augmenting device is illustrated as fluidic elements 82 and 84. Elements 82 and 84 have their receiver passages 86 and 88 connected to valve 90 and from valve 90 through passages 92 and 94 to the output fuel metering passages in parallel with the connections from fluid elements 56 and 58. Valve 90 is responsive to manifold vacuum similar to conventional carburetor power enrichment valves such that when manifold vacuum drops as wide open throttle condition is approached, the valve opens providing a power enrichment fuel augment to the carburetor mixing barrels.

OPERATION Operation will be considered with respect to the carburetor barrel 14 and fluidic elements 56 and 82, it being understood that a similar operation occurs with respect to mixing barrel 12 and fluidic elements 58 and 84.

At engine idle, throttle plate 26 is nearly closed, as illustrated, and a strong manifold vacuum is felt at idle jet 40 but only a weak vacuum exists at the main jet 36 as the quantity of air flow through the Venturi section is low. The strong manifold vacuum is transmitted through idle fuel restrictor 42, passage 44 to the output metered fuel passage 78. The main source of air is from main jet 36 and circulates through passages 44 to 42 and 40, with smaller quantities being added through bleed 76 through passages 78 and 44 out through idle restrictor 42 and idle jet 40. As the air flow increases due to a rise in engine speed, the amount of air bled into the system by main jet 36 is reduced by the increase in the level of vacuum applied at this point. Further increases in air flow cause the vacuum signal at the nozzle 36 to be stronger than that in con duit 44 which then causes fuel to be discharged from main jet 36. These varying vacuum signals are then transmitted to the receiver passage 72.

In view of the above, a partial vacuum, dependent on the relative sizes of the restrictors in the system, exists at the receiver passage 72 of the fluidic element and is also felt through passage 75 at the control jet 73. Vacuum at the control jet 73 is effective to partially deflect or pull the main fuel stream issuing from jet 60 to receiver passage 70 against the bias of the oblique jet 66. A portion of the fuel stream, an amount proportionately related to the partial vacuum existing in the output leg, will flow through metered fuel passage 78 and passage 44 to and out of idle jet 40. The idle fuel is mixed with air from restriction 76 to form an emulsified air-fuel mixture wherein both air and fuel quantities are controlled in amount. This mixture is delivered to barrel 14 downstream of throttle plate 26 where the air flow mixes with and carries the fuel charge to an engine to maintain idle operation.

As throttle 26 is progressively opened, the air flow in the barrel increases developing a progressively more effective vacuum in the Venturi section pulling on main jet 36 while idle jet 40 becomes less effective. Thus, fuel delivery at more wide open throttle position shifts automatically to main jet 36 and idle jet 40 becomes an insignificant factor. The partial vacuum in metered fuel passage 78, whether derived from the idle or main fuel system, is felt at control jet 73 to progressively deflect more of the fuel stream to receiver passage 70 according to engine needs.

Near wide open positions of throttle 26, the manifold vacuum downstream thereof has fallen sufliciently to actuate valve 90 and add a supplementary fuel quantity through passage 92 to metered fuel passage 78.

On engine shutdown the partial vacuum in passage 78 and at control jet 73 stops. During this condition it is to be noted that two effects insure a positive shutoff of fuel flow to passage 78 and the carburetor, even should the fuel pump continue to function or fluid inertia or gravity effects continue to supply fuel to the fluidic elements. First, the bias afforded by oblique jet 66 will always provide a bias to receiver passage 68 which dumps into reservoir 54 for return to the fuel tank. Secondly, the vertical elevation of passages 75 and 72 provides a static head of liquid fuel at the control jet 73 which will bias the main fuel stream to receiver passage 68 after the vacuum is lost in passages 78 and 72. If a minor quantity of fuel continued to enter receiver passage 70 after the partial vacuum is lost, it will tend to recirculate in a path from receiver passage 70, passage 75 and control jet 73 where it will tend to deflect the stream away from receiver passage 70.

In the arrangement described the fluidic elements are totally immersed in fuel so that only fuel may enter any control jets or reverse flow into the receiver passages. Consequently, the fluidic elements are isolated in liquid fuel. Air is introduced only into an output passage downstream of the fluidic elements and at a vertical elevation above the fluidic element and through a controlled air bleed. Thus the air into the system is always controlled and predictable while nevertheless sensitivity to vacuum air signals is obtained and without the use of costly transducer elements.

I CLAIM:

l. A fuel control system for an engine comprising in combination:

an air intake manifold;

a throttle valve disposed in said intake manifold for controlling air flow therethrough;

a fuel reservoir;

a proportional fluidic element having a main jet, a control jet and first and second receiver passages, said fluidic element disposed in said fuel reservoir and immersed in fuel; and

a metered fuel passage interconnecting one receiver passage of said fluidic element with the air intake manifold, said metered fuel passage having a portion vertically higher than the fuel surface level in the fuel reservoir in which said fluidic element is immersed.

2. A fuel control system as claimed in claim 1 including:

atmospheric vent means connected to said metered fuel passage at said portion vertically higher than the reservoir fuel level to, vent said metered fuel passage to the atmosphere.

3. A fuel control system as claimed in claim 2 including:

Venturi means formed in said intake manifold operative to develop a subatmospheric pressure related to mass air flow through the manifold;

said metered fuel passage terminating in said intake manifold in a region of subatmospheric pressure within said Venturi means.

4. A fuel control system as claimed in claim 2 wherein:

said metered fuel passage has a terminal point within said intake manifold posterior to said throttle valve.

5. In combination with a fuel system for supplying fuel to an air intake manifold at a region of subatmospheric pressure, having a first fluidic proportional beam deflection fuel metering element, said fluidic element having a main fuel jet, two receiver passages and at least one control jet, the improvement comprising:

a fuel reservoir having a controlled fuel level in which said first fluidic element is immersed;

metered fuel passage means interconnecting one receiver passage to the air intake manifold at a region of subatmospheric pressure, said metered fuel passage having a portion vertically above the fuel level in said reservoir; and

atmospheric vent means connected to said metered fuel passage at said portion above the fuel level to vent said passage to the atmosphere at that location.

6. The system claimed in claim 5 including:

a control jet in said fluidic element arranged generally transverse to the main fuel jet; and

conduit means interconnecting said metered fuel passage and said control jet at a point vertically above said control jet.

7. The system claimed in claim 5 including:

a second fluidic element immersed in the fuel in said reservoir having a main fuel jet, two receiver passages and at least one control jet; and

fluid connection means interconnecting said second fluidic element to said metered fuel passage means in parallel with said first fluidic element.

8. The system claimed in claim 7 including:

valve means responsive to subatmospheric pressure within the air intake manifold operative with said fluid connectake manifold; and

said metered fuel passage means has a terminal point within said Venturi means.

10. The system claimed in claim 9 wherein said metered fuel passage means has a second terminal point downstream of said throttle valve. 

1. A fuel control system for an engine comprising in combination: an air intake manifold; a throttle valve disposed in said intake manifold for controlling air flow therethrough; a fuel reservoir; a proportional fluidic element having a main jet, a control jet and first and second receiver passages, said fluidic element disposed in said fuel reservoir and immersed in fuel; and a metered fuel passage interconnecting one receiver passage of said fluidic element with the air intake manifold, said metered fuel passage having a portion vertically higher than the fuel surface level in the fuel reservoir in which said fluidic element is immersed.
 2. A fuel control system as claimed in claim 1 including: atmospheric vent means connected to said metered fuel passage at said portion vertically higher than the reservoir fuel level to vent said metered fuel passage to the atmosphere.
 3. A fuel control system as claimed in claim 2 including: Venturi means formed in said intake manifold operative to develop a subatmospheric pressure related to mass air flow through the manifold; said metered fuel passage terminating in said intake manifold in a region of subatmospheric pressure within said Venturi means.
 4. A fuel control system as claimed in claim 2 wherein: said metered fuel passage has a terminal point within said intake manifold posterior to said throttle valve.
 5. In combination with a fuel system for supplying fuel to an air intake manifold at a region of subatmospheric pressure, having a first fluidic proportional beam deflection fuel metering element, said fluidic element having a main fuel jet, two rEceiver passages and at least one control jet, the improvement comprising: a fuel reservoir having a controlled fuel level in which said first fluidic element is immersed; metered fuel passage means interconnecting one receiver passage to the air intake manifold at a region of subatmospheric pressure, said metered fuel passage having a portion vertically above the fuel level in said reservoir; and atmospheric vent means connected to said metered fuel passage at said portion above the fuel level to vent said passage to the atmosphere at that location.
 6. The system claimed in claim 5 including: a control jet in said fluidic element arranged generally transverse to the main fuel jet; and conduit means interconnecting said metered fuel passage and said control jet at a point vertically above said control jet.
 7. The system claimed in claim 5 including: a second fluidic element immersed in the fuel in said reservoir having a main fuel jet, two receiver passages and at least one control jet; and fluid connection means interconnecting said second fluidic element to said metered fuel passage means in parallel with said first fluidic element.
 8. The system claimed in claim 7 including: valve means responsive to subatmospheric pressure within the air intake manifold operative with said fluid connection means to selectively block and unblock fuel flow from said second fluidic element in response to subatmospheric pressure.
 9. The system claimed in claim 5 including: a throttle valve in said air intake manifold; Venturi means within said air intake manifold upstream of said throttle plate operative to generate a subatmospheric pressure that varies with quantity air flow through said intake manifold; and said metered fuel passage means has a terminal point within said Venturi means.
 10. The system claimed in claim 9 wherein said metered fuel passage means has a second terminal point downstream of said throttle valve. 